Digital predistortion for hybrid precoding architecture in millimeter-wave massive mimo systems

Millimeter-wave (mmWave) systems require massive antennas at both transmitter and receiver to reach desirable link budget. Analog-digital hybrid beamforming is a promising architecture since it significantly reduces the hardware cost while approaches the performance of digital beamforming. However, the nonlinear power amplifier (PA) introduces intermodulation interference and degrades the spectral efficiency. In this work, we use memory polynomial model for modelling mmWave PA and study the inter-beam and inter-symbol interference in hybrid precoding architecture. We also propose a digital predistortion (DPD) algorithm to mitigate interference. The proposed DPD reduces interference power by an order of magnitude and compared with system without predistortion, the proposed system can achieve up to 60% spectral efficiency.